Synchronizing system



Jan. 30, 1934-. KLAlBER 7 1,945,355

SYNCHRONI ZING SYSTEM Filed May 12. 1951 muzzmaummmmxmimia Fa g M 51INVENTOR FRIEDRICH KLAIB ATTORNEY Patented Jan. 3 0, 1934 UNITED STATESSYNCHRONIZING SYSTEM Friedrich Klaiber, Berlin, Germany, assignor toTelefunken Gesellschaft fiir Drahtlose Telegraphic in. b. H., Berlin,Germany, a corporation of Germany Application May 12, 1931, Serial No.536,714, and

- in Germany April 25, 1930 2 Claims.

The present invention relates to a means for picking up electricalimpulses in connection with synchronizing means of the kind speciallyrequired for the purposes of television work. In

5 television transmissions the electrical potentials which correspond tothe picture units or elements produced at the sen-ding end by means of aNipkow disk, are fed from the radio frequency receiver or the audiofrequency stage thereof, for instance, to a glow discharge orgaseous-conduction lamp or some other kind of light-conversion device,such as a Kerr cell, and the luminous fluxes produced by the latter arethen recomposed to create the desired picture by the aid of a Nipkowdisk or other suitable scanning instrumentality. The procedurepreferably is so arranged that for the purpose of insuring synchronousrunning of both Nipkow disks, a frequency is transmitted from thesending equipment (most conveniently by means of the same carrierfrequency or over the same line) to the receiver apparatus, and thisfrequency is suitably adapted to serve for 'the control of thesynchronizer apparatus. The output circuit of the receiver equipmentthus contains a synchronizing frequency in addition to the potentialscorresponding to the picture units or elements and it is this frequencywhich is arranged to control or insure the synchronous operation ordrive of the Nipkow disk in the receiver equipment. The chief point isto supply the synchronous driving device with a suitable synchronizingfrequency in a convenient way.

According to the present invention, the potentials operative in theoutput circuit of the audio frequency tube of the receiver apparatus andcoming in from the transmitter equipment control the light-conversiondevice in television receiver sets. This device may, for example, be aglow-discharge or gaseous conduction lamp. Ac- 40 cording to a modifiedform of device, part of these potentials coupled by potentiometer meansmay control at the same time a discharge vessel, the latter in turnserving to actuate a synchronizing means after all other frequencies(outside the synchronizing frequency) have been filtered out. Accordingto the invention, the potentials of the output circuit of the receiverapparatus most suitably are simultaneously fed both to thelightconversion device as well as to the grid of a triode tube, theamplified plate current thereof after having been rid of frequencies notrequired for synchronizing being fed to the synchronizing device.'

Preferably in the plate circuit of the thermionic tube controlled by theoutput-circuitpotentials of the receiver, there are provided accordingto this invention filtering means of a kind known in the prior art sothat there will be imparted to the grid of the next tube whose platecurrent serves to actuate the synchronizing device, only potentialshaving the frequency intended for synchronizing. In this mannerconditions are made such that the potentials controllingthe'lightconversion device will not be distorted by the means providedfor filtering the synchronizing 55 frequency, and above all thatabsorption of the synchronizing frequency from the output circuit of thereceiver will not be attended with energy consumption.

According to one object of this invention, the synchronizing frequencypreferably consists of a frequency inevitably resulting at the sendingend from the process of scanning the picture, pre eminently a frequencywhich results by reason of the fact that darkness prevails for a shortwhile between. the instant of slipping over a perforation in the Nipkowdisk at the end of a line and the entrance of the next hole of the nextline into the picture surface. For this purpose, the picture window maybe enlarged somewhat in 30 width than what would correspond to thebreadth or distance between two holes of the Nipkow disk. The frequencythus obtained is equal to-the product of the picture unit number persecond and the number of the lines, in other words, equal to 375 Hertz(cycles) if the Nipkow disk at the sending end revolves 12 times persecond, and if it is provided with 30 holes. Accordingly, filter meansshould be provided in the plate circuit, of a thermionic tube servingfor the production of the synchronizing means (frequency) or in the gridor plate circuit of an amplifier tube associated therewith, said filtersbeing designed to permit the propagation only of this particularfrequency.

Now, according to the invention the ensuing potentials of synchronizingfrequencyare fed to two windings being respectively fitted upon the twopole-shoes of an iron-core. These pole-shoes in well known manner aredisposed opposite the keeper of a medium frequency generator which isdriven by a motor. The windings are used at the same time to tune theoutput circuit of the tubes controlling the synchronizing device to thesynchronizing frequency, and to complete or perfeet the filtering of thelatter. The discharge vessel serving for the producton of thesynchronzing frequency, and the light-conversion device, according tothis invention, are fed from a joint potential-source, most preferablyfrom the net work potential, by way of a rectifier in case of analternating current supply line. The direct current circuit of theassembly is separated from the crest value of the alternating currentpotential will always be just higher than the extinction potential ofthe said tube or lamp.

The light conversion device conjointly with the tubes to produce thesynchronizing frequency, the means establishing connection with thenetwork or supply line and a change-over switch for making connectionsfor radio or picture transmission or-reception are disposed inside ajoint casing.

One embodiment of the invention is illustrated in Figs. 1 to 4, wherein:Fig. 1 shows the assembly of the arrangement; Fig. 2 illustrates the keydiagram; Fig. 3 illustrates one form of synchronizing device in furtherdetail; and Fig. 4 represents a modification of Fig. 3 for filtering thesynchronizing frequency.

Referring to Fig. 1, 1 denotes the radio frequency receiver comprisingthe last audio frequency stage tube 2 together with output terminals 3and plate potential 4 bridged by a con- I denser. The filament of tube 2is grounded, for

instance. 5 is a casing in which the televisoi outfit of this inventionis accommodated. Opposite the Nipkow disk 6a is a gaseous-conductionlamp 6 being indicated only schematically. This lamp is fed with directcurrent potential from the voltage source '7 (supply-line connectionmeans). The output terminals 3 of the receiver 1 and the input terminals8 of the television receiver 5 are inter-connected, for instance, by

-means of a two-conductor cord. By means of the change-over switch 9 theoutput potentials of tube 2 may be applied to the loudspeaker 10 orterminals 11. United with terminals 11 is the television receiverapparatus. The alternating current potentials acting across theresistance 12 from tube 2 are supplied by way of the blocking condenser13 to gaseous-conduction lamp 6, and by way of the blocking condenser 14to the tube 15 serving for filtering out the synchronizing frequencywhich is likewise supplied from the potential source 7. As to the rest,all of these connections are dagrammatically indicated in key diagramsof Fig. 2.

Gaseous-conduction lamp '6 and the tubes 15 and 1.6 serving for theproduction of the synchronizing frequency are fed with the necessarypotential from the supply-line 17 by the aid of trans;

former 18 and rectifiers 19. Numerals 20, 21 denote windings for theheating of the rectifier 19 or the tubes 15, 16. The filter circuitconsisting of choke coils 22, 23, and the condenser 24 serves forsmoothing the potential supplied to the gaseous conduction tube and theplate potential for the tubes 15, 16. The gaseous conduction tube is fedwith direct current by way of resistance 25 and the variable resistance26. In the negative lead for the gaseous conduction lamp there arefurther included potentiometric resistances 27 for tapping the gridbiasing potential for the tube 15. The latter is fed with grid biasingpotential by way of resistances 28 and 29. In order to obtain definiteplate potentials for the tubes 15 and 16, there are also provided theseries resistances 30 and 31 because relatively high potentials arerequired for the gaseous conduction tube. Numerals 32 to 36 representshunting capacities. The plate circuit of tube 15 is coupled by means ofthe resistance 37 and capacity 38 with the grid of tube 16, the tube 16serving at the same time for the amplification of the synchronizingfrequency. Between the grid and the filament of tube 16 is connected anoscillation circuit tuned to the synchronizer wave and comprisinginductance 39 and capacity 40. This oscillation or tuned circuitconstitutes a high reactance only for the synchronizing frequency, whilea very low one for all other frequencies. 7

Includedin the plate circuit of the tube 16 is a transformer 41; thesecondary winding of the same is arranged in parallel with condenser 42,while being in series relation as shown with the windings 43 and 44 ofthe synchronizing device which may be connected either in parallel orseries. The circuit consisting of the secondary winding of thetransformer 41, the capacity 42 and the windings 43, 44, is so tuned(potentialresononace fashion) that in the-plate circuit of tube 16 ahigh resistance is transferred only for the synchronizing frequency,with the result that the windings 43, 44 substantially are energizedonly by the synchronizing frequency. The'synchronizing device isillustrated in more detail in Fig. 3.

Referring now to Fig. 3, 45 denotes the armature of a synchronousgenerator which is propelled by a motor (not shown). Opposite the saidsynchronous wheel or armature 45 are mounted the. pole-shoes wrappedwith the windings 43 and 44 in away as'shown in the drawing. The ironbody or core 46 is further provided with a winding 47 which must be fedwith direct current to obtain a desired flux of definite value,preferably from the potential of the rectifier 19.

An arrangement of the type shown by Fig. 4 has proven particularlysuitable for the filtering out of the synchronizing frequency from theplate current of the tube which controls the synchronizing deviceincluding windings 43, 44. The plate circuit of tube '16 as shown byFig. 4 contains in series the windings 43, 44 and the condenser 48. Thisbranch of circuit is tuned to the synchronizing wave series-resonancefashion. Plate potential is supplied to the tube '76 by way of the chokecoil 49 which by the aid of the capacity 50 is likewise tuned to thesynchronizing frequency.

To prevent synchronizing frequency from flowing off by way of the directcurrent winding 51 3 of the synchronizing device, a choke coil 46 tunedto the synchronizing frequency by the aid of condenser 47 may beinserted in the lead connecting the winding and the source of potentialso that the fly-wheel circuit 46, 4'7 acts like a stopper for j l. Asynchronizing system for television com-' prising an image reproducingdevice, means for rotating theimage reproducing deviceand asynchronizing device for controlling the rotation of the driving elementfor rotating the image reproducer, means for receiving combined imageand synchronizing signals, means for supplying the received signals tosaid image reproducing device to produce electro-optical reproductionsthereof, a vacuum tube circuit connected with said synchronizing device,means for supplying the received signals also to said vacuum tubecircuit, a portion of said vacuum tube circuit tuned to saidsynchronizing signals, and means including a portion of the saidsynchronizing device connected with the said vacuum tube circuit forseparating said synchronizing signals from said image signals.

2. A synchronizing system for television comprising means for receivingcombined image and synchronizing signals, a rotary synchronizing elementfor insuring proper positioning of the electro-optical effects resultingfrom the received image signals, said synchronizing device havingwindings adapted to be energized by said synchronizing signals, a vacuumtube circuit having a portion thereof tuned to the synchronizing signalconnected with said synchronizing device windings and with the source ofsaid received image and synchronizing signals whereby said windings areutilized as a filter device connected with said vacuum tube circuit toseparate the synchronizing signals from the image signals and cause thesynchronizing signals to exert a speed correcting impulse uponsaidwindings.

FRIEDRICH 1:

